1. Field of the Invention
The present invention relates to an apparatus and method of detecting a pulse wave, and particularly, to an apparatus and method searching a proper artery position to detect a pulse wave at the searched artery position.
2. Description of the Related Art
A pulse wave is detected based on pressure information that is a voltage signal obtained from an pressure detecting element pressed against a human body surface above an artery. The pressure information shows a pulse pressure, the pulse pressure originates from a change in arterial volume caused by pressurization and a waveform showing the change is acquired as a pulse wave. As pulse wave detecting apparatuses, there have been available an apparatus determining whether or not a pressurization position is proper based on whether or not an amplitude of a pulse wave when a pressurization force reaches a predetermined level is a predetermined value or less (for example, see patent document 1, which are the specification and drawings of Japanese Unexamined Patent Publication No. 01-285244) and an apparatus having a function determining whether or not a pressurization state of a pressure detecting element is proper (for example, see patent document 2, which is the specification and drawings of Japanese Unexamined Patent Publication No. 06-90912).
Since the prior art pulse wave detecting apparatuses, however, have no function specifying positions of hard members such as a bone and a tendon at a pressurization site and therefore, have difficulty detecting a pulse wave at a proper artery position, a detected pulse wave includes an artifact pulse wave, which causes a high detection precision to be obtained with difficulty. The term “artifact pule wave” means an AC noise component in a voltage signal caused by a hard member.